


Swim Into My Heart

by PeaceLilies



Category: Voltron: Legendary Defender
Genre: Falling In Love, Fantasy, M/M, Mermaids, Merpeople, mer!Sheith, modern day setting with a fantasy twist
Language: English
Status: Completed
Published: 2021-02-11
Updated: 2021-02-11
Packaged: 2021-03-17 23:08:30
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,667
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29358495
Author URL: https://archiveofourown.org/users/PeaceLilies/pseuds/PeaceLilies
Summary: Allura is a marine biologist who cares for injured mers that can't return to the sea and has one mer in particular that she adores and just wants to be happy
Relationships: Keith/Shiro (Voltron)
Comments: 48
Kudos: 137





	Swim Into My Heart

**Author's Note:**

> This is one from deep in the archives! Thank you as always to [Ren](https://twitter.com/lilflowerbot) for encouraging me to publish my stuff and for writing an amazing follow up to this lil fic!
> 
> Enjoy!

Since she was a little girl, Allura had had mers. Her father had been a marine biologist, studying the various creatures of the sea, and his favorite had always been mers. Having grown up in a lab, Allura was used to seeing all kinds of amazing creatures, but none so intelligent or playful or mischievous as the mers. 

Her father would take in mers who were too badly injured to return to the sea and she had helped care for them. She had grown to love mers as much as her father and had continued his legacy. She had five of them in total, all having recovered from their injuries, but unable to return to their natural habitat due to significant damage to fins and limbs. 

Four of them were a small band of bonded mers: James, Ina, Nadia, and Ryan. They had been rescued from a fishing net, James and Ryan having been trapped with fish hooks, tearing fins, while Ina and Nadia had suffered damage to their gills. All four were doing very well, but needed care and maintenance that could not be offered in the wild. 

Allura loved her mers and wanted them to receive the best care. While the tanks weren’t as big as the sea, they were large enough to accommodate the mers, and it was perhaps a blessing that many of her rescues were young, and so growing up in a tank was an easy adjustment. 

Her oldest mer, Shiro, lived in a tank all his own. He had been caught during a rescue effort after an oil spill. She had actually rescued him and his bonded mate. They had both been very, very sick, and she had spent much of her time nursing both of them back to health. Shiro’s mate hadn’t survived, having been poisoned and suffering severe damage from the oil. Shiro had been heartbroken and Allura had done all she could to help heal Shiro’s body and his heart. He had pulled through, though he had lost an arm, and while they had a strong bond, having grown close over the time that she had cared for him, Shiro held an air of melancholy about him. 

Even so, he was a sweet and intelligent mer. He felt so comfortable with her that he would take food from her fingers. She did her best to create games and puzzles to keep him occupied and they had learned to communicate using a sign language of sorts. 

She had tried to introduce him to the other mers, and while he was friendly and was happy to help guide the younger ones, he seemed to prefer his solitude and quietness. 

_Too rowdy for me_ , he had told her, though Allura suspected that he still mourned. 

She made her rounds that evening, after a rather quiet day of overseeing some interns, making sure everyone was fed and doing well. 

Shiro was sitting on the larger rock in his tank that served as his sleeping spot (inside the cave) and his favorite perch (right on top). He had the puzzle box she had given him on his lap and he turned when her shadow fell across the tank. He swam over, box in hand, smiling warmly. 

He held out the box and Allura chuckled. 

“All done are we?” she asked and Shiro nodded, releasing the box so that it floated to the top of the tank.

_That one was hard, but I got it. Thank you_ , he told her. 

“I knew you would. I’ll have another one for you tomorrow,” she replied with a chuckle, lifting off the top of the tank, and giving Shiro his dinner, some nice shrimp and scallops, as a treat. Shiro swam up to meet her fingers, resting his hand on her knuckle for a moment, his way of saying thank you, and gathered the food.

Allura enjoyed her talks with Shiro. He was no more than six inches long, rather large for a mer, but small by human standards. He had a scar across his nose and was very strong, having been swimming with just one arm for so long. His hair had been black when she had found him and had turned white from the stress his body had been under from being ill and losing his mate. He was handsome, with a strong face, intelligent gray eyes, and a beautiful deep purple and white tail and fins. There were scars all over his torso and tail, illustrating the challenges he had had to endure. 

She knew a fair amount of his history and where he had come from. It had seemed a tumultuous life for him, considered a protector amongst his school, and while he had expressed some homesickness for the sea, he understood that he would not survive if he were to return. 

“We’re going to have a new mer tomorrow,” she said as Shiro ate. He looked at her, mouth full of shrimp, and arched a silver eyebrow at her, curious. 

“Hunk has been caring for him the past few weeks, he was severely wounded in some sort of incident. We’re not sure what happened. He’s rather prickly. I’m going to see how the Mer Force and he get on,” Allura explained, “and I’ll have you meet him as well.” 

Shiro nodded happily, always excited to meet new mers, to help them acclimate, even if he stayed by himself. They talked a little more, Allura promising to bring Shiro another, harder puzzle box, and some tools for him to craft, as that was something he seemed to enjoy, before she bid him goodnight. 

***

The next morning, Hunk came over with the new mer. 

“I don’t know, Allura. You might have to keep this one by himself. He’s...kinda’ feisty,” Hunk explained, holding up the clear tank that housed a beautiful little mer. 

He flared and puffed up at seeing her, baring his fangs. He had a mass of jet black hair and was a striking, gorgeous red. He had a scar on his cheek and shoulder and Allura could see tears in his fins. 

“Oh he certainly is,” she replied, looking away from the mer, up to Hunk, “he’s lovely though.”

“Yeah, well, don’t let his looks fool you. He chomped me good a few times. I think we came to an understanding...sort of...but...I don’t know. I don’t think he’s going to play very nice with others.” 

Allura nodded thoughtfully. 

“Well, we can test out and see how he does with the mer squad...and I’ll introduce him to Shiro, too. Shiro always has a way with the newcomers.”

She took the tank from Hunk, looking into the tank again. The little mer wasn’t done displaying, warding her off through the glass, and she hummed. 

“Don’t worry. You’ll be alright. I promise.” 

She transferred the little mer, known as Keith, to a slightly larger acclimation tank, with a few hiding places so that he didn’t get too stressed from all of the newness he was experiencing, while speaking with Hunk about where he had come from and what his story was. 

It seemed that Keith had washed up on a beach and had been picked up, luckily, by a group of bird watchers who had been cataloging a pair of snowy owls who had made a nest there. He was unconscious, bleeding, and looking like he had been in a terrible fight of some kind. 

He’d been with Hunk for nearly a month and they had seemed to find a begrudging truce. 

Allura brought the tank to where the small school of mers resided. Nadia and Ina seemed curious, James and Ryan more hesitant. Keith flared and puffed immediately, making the girls fall back. Ryan and James flared up in response, Ryan staying between the girls, while James moved closer to the glass, fangs showing. He and Keith had a standoff, bumping against the glass, before Nadia tugged James back. The four mers huddled together, moving further from the glass. Keith, seemingly satisfied with this response, eyed them wearily, but relaxed slightly, and scoped out a hiding spot, before slipping grumpily into one of the caves. All that could be seen in the shadows were bright violet eyes. 

“Well, that went as well as it could have, I think,” Allura said and Hunk just shrugged. 

***

Over the next several days, Allura tried, in spectacularly unsuccessful fashion, to ease Keith into the tank with the other mers. But no one was having it. If Keith was going to be this aggressive and James was responding in kind, she knew an all out brawl would ensue, and that would not be good for anyone. 

She moved Keith away from the tank and decided to finally bring him to Shiro. 

Shiro had been asking about the new mer and knew that there seemed to be some discontent. He was eager to help if he could and at this point, it certainly couldn’t hurt. 

“Alright, Shiro. This is Keith. Keith, this is Shiro. Keith seemed to be having some trouble getting to know everyone so...let’s see if maybe you can help…”

Shiro had swam up to the glass, where Allura had put the two tanks close together. Keith looked like he might flare, but then stood down, to Allura’s surprise. He wasn’t relaxed by any means, but he wasn’t acting outwardly aggressive. Shiro held up his hand to the glass, looking curious and interested at Keith. He made a soft, singing sound, something in the mer language. 

Keith tilted his head, hearing him, but didn’t respond. Allura watched Shiro sing again, before swimming in a figure eight by the glass. He was calm, gregarious, and Keith seemed somewhat interested, but definitely unsure. 

He didn’t sing back, just watched Shiro, eyes darting to Allura, and then he swam away to hide in his cave. 

Shiro looked at Allura and gave a little shrug, before signing with his hand. 

_He’s scared._

Allura nodded, sighing softly, and smiled at Shiro. 

“I’ll leave him in your capable presence, Shiro. I think he’ll come around.” 

***

Shiro had met and known many mers in his lifetime. He had come to peace with knowing he would not return to his people and that he was destined for his life here. It was not the sea...but he appreciated a caretaker who did not allow him to rot. Allura was a wonderful human, though Shiro had not known many, and she had helped him greatly. 

He was content to stay by himself, telling himself that it was better, being able to do as he pleased, occupied with crafting and puzzle solving and talking with Allura. He still felt the pang of loss of no longer having a mate, but he was glad to have Allura and to have helped the other mers become more comfortable in their new home. 

Shiro had been excited to learn of meeting a new mer. It had been quite some time since they had met anyone new. When Shiro had seen him, he had seen a frightened soul. He was on the defensive, wanting to protect himself in a strange place, which Shiro could understand, and he had not sung back, meaning he was not trusting. 

He looked young, but not a child. He had wounds, showing he was a warrior, or perhaps a trouble-maker, maybe both. His coloring suggested a fighter. He would not have come to Allura if he could be returned to the sea, so Shiro hoped that the newcomer would warm to him eventually. 

Shiro would go to the side of the tank and greet him every morning, singing to him his greetings. He would see if he wanted to play, darting around his tank. The new mer was no longer displaying, just watching Shiro with interested, if somewhat uncertain, violet eyes. 

Shiro was intrigued by him and hoped that he may soon begin to warm so that he would be able to get to know more about him. He tried to share some about himself and while the mer seemed curious, he wouldn’t directly engage, and he would hide every time Allura came by. 

Shiro explained to him who she was and that she was here to help them, not to hurt them. He would take his food from her hand, showing his trust, and they would talk, while Shiro could feel the mer’s eyes on him, watching. 

It was while Shiro was working on the puzzle box that the mer sang at him. 

“What are you doing…?” he asked, floating by the glass where the tanks sat side by side, watching. 

“I’m working on a puzzle,” Shiro replied, shifting over on his rock, so that Keith could see better. 

“She gives you puzzles…?”

Shiro laughed softly and nodded. 

“Yes. It keeps me occupied, my mind sharp. Allura is very smart. These are challenging.” He laughed again, setting the box down. 

The mer watched him, blinking at him curiously. 

He was smaller than Shiro, but strong, a defiant look to his eyes, his face sharp. 

“What happened to your arm…?”

Shiro touched his shoulder, a little self-conscious, but smiled at the mer. He explained his story, hoping that it may ease the mer into comfort, and know that he wasn’t alone, that he was in good hands. 

He seemed to take this information in, mouth open slightly in awe. 

“It seems you might know a thing or two about battles…” he said, trailing off, not knowing the mer’s name. 

“Keith,” he replied, his head snapping to the side a moment later when Allura entered the room. Keith stole a quick glance at Shiro, before he went hiding back under his rock. 

Shiro smiled softly, holding a hand up in farewell. 

_Keith,_ he thought to himself, pleased. 

***

Allura watched in amazement as Keith became more and more comfortable with Shiro. He started venturing out of his cave when Shiro would greet him. They were talking to one another, playing games. A sweet camaraderie seemed to have developed, though Keith would hide away any time she was near. 

_He’ll come around_ , Shiro had assured her. 

And he did, slowly. He would peek out further and further from his rock when she would bring him food. Though he wouldn’t take it from her hand, he wasn’t shying away, and that was a good sign. 

He and Shiro would eat together, staying by the glass where their tanks met, singing back and forth. She was so curious about what they were discussing, but settled for just allowing them to bond. 

As Keith became more comfortable, Allura noticed that he would watch Shiro so intensely. She had thought that it could have been from aggression, but as she was seeing them together more and more, she came to realize that...Keith was lonely. 

His violet eyes tracked Shiro’s movements, watched him as he worked on a puzzle, or crafted, in his own world. Keith wanted to join him! 

Allura decided to broach the subject with Shiro when Hunk had come over to help her clean the tanks. 

“Shiro...what would you say if I...introduced Keith to your tank…?” she asked gently, sitting by the tank, close to the glass. 

Shiro swam over, digesting this information with large, gray eyes.

_Really?_

Allura nodded, smiling softly. 

“I know that it’s been a long time since you’ve had someone in your tank with you and I by no means am saying this to pressure you, but...I think Keith is lonely and...perhaps...you are, too. I feel like it would be nice for you to have a friend…”

Shiro smiled warmly back at her, nodding enthusiastically. 

_Yes. Please. I would like that._

“Alright, good. It’s settled then. Let’s give it a go.” 

_Now?!_ Shiro asked, puffing out a little in anxiety, which made Allura giggle. Shiro was never flustered. He swam around in circles, before darting into his cave, rocks spewing out. 

_I have to tidy!_

Allura giggled again, watching Shiro dart around his tank, seeming to clean and organize and straighten. 

“He’ll love it, Shiro. I think it’ll be enough that he’s with you.” 

***

Keith floated grumpily, arms crossed over his chest, in the small bowl that he had been placed in while his tank was being cleaned. He didn’t mind Hunk that much and Allura was starting to grow on him a little, mostly because Shiro liked her, but he just wanted to stay in his tank. 

What he really wanted was to go back to the sea...but with his bum fin, there was no way he would make it. And besides...he liked Shiro. 

When he had first been brought to the lab, he was angry and scared and wanted nothing more than to go back to the sea. The more he realized that the likelihood of that happening was basically zero, he had lashed out. 

He didn’t want to make friends or know anyone...even if they were other mers. But Keith certainly hadn’t been expecting Shiro. 

He was...big and strong...wearing battle scars like trophies. He was kind and soft-spoken...and...funny. Keith hadn’t been expecting that either. Shiro had been through so much and having made his peace with his fate...it seemed to calm something in Keith. 

He wasn’t alone. Which he hadn’t realized he’d needed to know until then. He wanted to be with Shiro. To share the same space. To know him. He’d been wanting that for a while now. But stupid Allura hadn’t let them share a tank and he didn’t know if she even would. He didn’t want to ask and he didn’t know if Shiro had…

He wished he knew if Shiro even wanted to share the same space as him. It seemed like he might. Maybe. Always saying hello and playing and talking with Keith. 

“Alright, Keith. Let’s try this,” Allura said, lifting the bowl Keith was in. He was confused and huffed, looking up at her through the water, her visage slightly obscured. 

“Up we go,” she said, a net slipping into the bowl and scooping Keith up. He made a sound of protest before she gingerly started lowering him into Shiro’s tank. 

It took him a moment to realize what was happening, allowing him to acclimate to the water...but _he was in Shiro’s tank!_ He started to struggle, trying to find a way to _get out_. 

“Keith, Keith! Don’t struggle,” Shiro said, sounding concerned. Keith saw him, reaching out and gently touching Keith through the netting. 

Shiro was touching him. _They were touching_. Keith started gnawing at the net, desperate enough to bite through it if he had to. 

“Oh goodness gracious, Keith!” Allura said, gently tipping the net. Keith swam out eagerly making a beeline for Shiro. Allura gasped. 

Keith threw his arms around Shiro, holding him tight. He felt Shiro’s arm curl around him, his cheek resting against the top of Keith’s head, their tails curling together. 

“Shiro,” Keith hummed, feeling the rightness of being able to touch him, to feel him there, solid and sure. 

“Keith,” Shiro replied, giving him a squeeze, “welcome.” 

Keith looked up at Shiro, smiling brilliantly, before hugging him close again. 

Maybe this wasn’t going to be all that bad after all.

***

Shiro spent the day showing Keith his tank. He followed him around like a guppy, seeming so interested in Shiro showing him his favorite spaces, his newest puzzle box, things he was crafting. 

Allura was going to add a few more alcoves for them, had mentioned maybe a bigger tank even, but Shiro was happy to have Keith with him. It felt so... _right_. 

Shiro had been with his bonded mate for long enough that his loss had left a hole in his heart. He did not think that that hole would ever be filled. And yet...watching Keith...Shiro thought...maybe he was wrong. 

He watched Keith scouting the tank, checking out the territory, a little puffed up...protective. It was...impossibly sweet. They talked for hours, just learning about one another, until Keith dozed off, and fell asleep. 

He was young and solemn, having been through so much in such a short amount of time. Shiro hoped that he could make him feel comfortable and that they could enjoy one another’s company. Keith had seemed excited and Shiro was, too. 

The next morning, Shiro woke up to find Keith swimming the perimeter of the tank. Shiro chuckled to himself, stretching, and coming out of the cave. Keith turned, smiling happily, and swam over. 

“Good morning,” Shiro greeted as Keith swam around him. 

“Good morning,” Keith replied, coming back around, seeming satisfied that Shiro wasn’t any worse for wear, “did you sleep well?”

“Well enough,” Keith replied and gave a little smile, “just adjusting to being in a new place.” 

Shiro nodded in understanding, smiling back at him warmly. 

“Of course, that makes sense.” 

They spent the morning swimming idly and talking. Allura brought breakfast and Keith hid behind some sea grass, while Shiro chuckled softly, and took the food from her fingers. Keith peeked out, watching them. 

“You trust her,” he asked, coming out from behind the grass, and accepting the food Shiro gave him. 

“Of course,” he replied, “she’s taken really good care of me. And she’s nice. You’ll like her.” 

Keith didn’t seem too convinced, but he took a bit of food and chewed thoughtfully.

“Maybe…” he said, his mouth still partially full.

Breakfast finished, Shiro showed Keith how he would tidy up the tank, and then worked on the puzzle Shiro had. 

They were getting close to figuring out how to solve it when the tank’s automatic cleaner turned on. 

Shiro dropped the puzzle box, diving into his cave, huddling in the back. He hated the cleaner. He knew what it was and what it was for...but it was so loud...and disconcerting. He was pretty good at knowing when it would turn on, but seeing as how there were two of them, he supposed the timing would change. 

He peeked out from the cave, seeing Keith all flared up, as if he were going to attack the filter. 

“Keith! Don’t do that!” Shiro called, his hand resting on the lip of the cave, “it’s just the filter…”

Keith turned, looking ready for a fight. 

“But you’re scared,” he said. 

Shiro nodded, holding his hand out. 

“Can you stay with me instead?” he asked. 

Keith blinked, confused, maybe a little surprised, perhaps never having thought that there may be another option other than fighting. He relaxed and swam over, joining Shiro in the cave.

Shiro was honestly relieved, glad to have someone with him, and to not be alone. 

“I’ll protect you,” Keith said, wrapping his arms around Shiro, holding him. Shiro nodded, wrapping his arm around Keith in return, settling his head against his shoulder, and closed his eyes. 

“I know…” 

Keith gently petted Shiro’s hair, his tail curling around Shiro’s, keeping him anchored and safe.

***

Things seemed to shift after the time with the filter. 

Keith started grooming Shiro, curling up with him when the tank was cleaned, helping him with his puzzles, and playing other games with him. Shiro started showing Keith that those who visited were friends of Allura’s and could be trusted. 

Keith, slowly but surely, started coming up to the glass with Shiro, greeting Allura or her friends when they came by...even taking food from her hand sometimes. Shiro was proud of him and was glad to have a companion.

Allura moved Keith and Shiro to a much larger tank. While Keith hadn’t been happy to be separated from Shiro while Allura transferred them, he seemed very pleased to be in a bigger tank, with more hiding spots to explore. 

Shiro liked that it was _their_ space now, as opposed to just Shiro’s. He slowly came to learn that they were bonding...maybe even already bonded. Shiro liked Keith. Maybe...kind of...loved him. He was a little prickly at first, but so open and sweet and fun when he was comfortable. He made Shiro feel safe, which was something he hadn’t truly felt in a long time. 

It seemed he wasn’t the only one who felt that way, as a few days later Keith presented Shiro with a small gift, a shell on a string made of tiny beads. 

“I asked Allura for the materials,” Keith said softly, holding the necklace out for Shiro, “I...wanted to give you something. To say thank you. And...um...to ask if you, maybe...wanted to be mine…?”

Keith was so rarely unsure of himself. Shiro felt so proud of him for asking Allura for things and so grateful that Keith felt so comfortable and safe around Shiro that he could be so vulnerable. Shiro couldn’t help but beam at him and wrap his arm around him to hold him close. 

“Of course I do,” he said, feeling tears in his eyes, “of course. I’m so glad.”

Keith seemed to catch on, coming out of his daze, and wrapped his arms tight around Shiro. He pulled back a little, smiling hugely, and leaning in to press kisses to Shiro’s face, making him giggle. 

“Shiro,” he cooed, humming happily as Shiro rubbed their faces together. 

“Keith,” Shiro cooed back. 

They pulled back just enough, Keith placing the necklace around Shiro’s neck, resting his hand over the shell on Shiro’s chest.

“Can I kiss you?” Keith asked and Shiro giggled, because he already had. 

“Yes, of course.”

Keith leaned in, pressing a gentle kiss to Shiro’s mouth. It was as sweet and tender as he was and Shiro leaned into it, feeling all of the love that had grown between them since Keith had arrived. 

“You’re so handsome,” Keith blurted when they pulled apart, violet eyes wide and sincere. 

Shiro laughed, blushing deeply, and rested his forehead against Keith’s. He gently stroked his fingers along his side, nuzzling their noses. 

“So are you. You’re beautiful,” he replied, pulling away slightly to lean in and kiss the scar on his cheek. 

He watched Keith blush and couldn't help but chuckle. Keith put his arms around him again, tails coiled, and tucked his head under Shiro's chin. 

"Thank you," he heard Keith whisper. 

Shiro tilted his head down to kiss into his hair, closing his eyes. He was the grateful one. So thankful for small miracles and circumstances that were out of his control, but had brought them together. 

Keith lifted his head and Shiro leaned in to kiss him. He wished he had his other arm, so that he could encompass all of him, keep him close. He wanted to love and soothe and it surprised him how much he had wanted this. Wanting to love and be loved. 

He felt Keith cup his face, stroking his cheeks, and he smiled at him softly, turning his head to kiss his palms. 

“Sweet one,” he murmured as Keith nudged their faces. 

“You’re the sweet one,” Keith murmured back, pulling away so he could take Shiro’s hand, gently guiding him back toward one of the larger caves. 

“Sweet and kind and funny and wise…”

Shiro blushed and Keith laughed, warm and confident. 

“I wasn’t sure that I would ever be okay with being here. I didn’t want this...to be hurt, or stuck in a tank, but...I’m so glad I met you and that I get to spend the rest of my life with you. Thank you for teaching me and showing me that I’m safe here...for taking a chance on me.”

“No thanks, required,” Shiro soothed, squeezing Keith’s hand, “I’m so excited to spend the rest of my life with you, too…thank you for protecting me...”

“It’s my honor,” Keith replied, eyes alight. Shiro couldn’t help but kiss him again, wishing once more that he had two arms to hold Keith with...but he would do the best he could.

**Works inspired by this one:**

  * [And Build A Home](https://archiveofourown.org/works/29371020) by [littlegraybunny](https://archiveofourown.org/users/littlegraybunny/pseuds/littlegraybunny)




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